class_docstr: a immutable object holding a source code fragment,
  possibly deindenting it.
code: def __getslice__(self, start, end):
      newsource = Source()
      newsource.lines = self.lines[start:end]
      return newsource
  
imports: from __future__ import generators
  from bisect import bisect_right
  import sys
  import inspect, tokenize
  import py
  from types import ModuleType
label_desc: Use image node_id 5 for calling the Source obj's underlying member method code with example usage: obj.__getslice__(start, end) and returns: newsource